Stent for use in a stent graft

ABSTRACT

A stent-graft for insertion into a body lumen, such as a blood vessel, is utilized in order to repair such lumen. The stent-graft includes a substantially cylindrical hollow expandable stent comprising a plurality of interconnected struts. The stent has a distal end and a proximal end, and an interior surface and an exterior surface. At least one strut of the stent has first and second apertures extending therethrough from the interior surface to the exterior surface. The stent-graft also includes a graft member covering a predetermined portion of least one of the interior surface and the exterior surface of the stent. In addition, the stent-graft further includes a staple for attaching the graft member to the stent. The staple has a crown and two legs extending therefrom. At least one of the legs of the staple extends through the graft material and through the first aperture. Both of the legs are bent inwardly towards said crown such that they evert back and extend through the second aperture.

FIELD OF THE INVENTION

The present invention relates to percutaneously delivered stent-graftsfor repairing abdominal aortic aneurysms.

BACKGROUND OF THE INVENTION

An abdominal aortic aneurysm is a sac caused by an abnormal dilation ofthe wall of the aorta, a major artery of the body, as it passes throughthe abdomen. The abdomen is that portion of the body which lies betweenthe thorax and the pelvis. It contains a cavity, known as the abdominalcavity, separated by the diaphragm from the thoracic cavity and linedwith a membrane, the peritoneum. The aorta is the main trunk, or artery,from which the systemic arterial system proceeds. It arises from theleft ventricle of the heart, passes upward, bends over and passes downthrough the thorax and through the abdomen to about the level of thefourth lumbar vertebra, where it divides into the two common iliacarteries.

The aneurysm often arises in the infrarenal portion of the diseasedaorta, for example, below the kidneys. When left untreated, the aneurysmwill eventually cause rupture of the sac with ensuing fatal hemorrhagingin a very short time. High mortality associated with the rupture has ledto the present state of the art and the trans-abdominal surgical repairof abdominal aortic aneurysms. Surgery involving the abdominal wall,however, is a major undertaking with associated high risks. There isconsiderable mortality and morbidity associated with this magnitude ofsurgical intervention, which in essence involves replacing the diseasedand aneurysmal segment of blood vessel with a prosthetic device whichtypically is a synthetic tube, or graft, usually fabricated of eitherDACRON®, TEFLON®, GORTEX®, or other suitable material.

To perform the surgical procedure requires exposure of the aorta throughan abdominal incision, which can extend from the rib cage to the pubis.The aorta must be cross-clamped both above and below the aneurysm, sothat the aneurysm can then be opened and the thrombus, or blood clot,and arterioscleriotic debris removed. Small arterial branches from theback wall of the aorta are tied off. The DACRON® tube, or graft, ofapproximately the same size of the normal aorta is sutured in place,thereby replacing the aneurysm. Blood flow is then reestablished throughthe graft. It is necessary to move the intestines in order to get to theback wall of the abdomen prior to clamping off the aorta.

If the surgery is performed prior to rupturing of the abdominal aorticaneurysm, the survival rate of treated patients is markedly higher thanif the surgery is performed after the aneurysm ruptures, although themortality rate is still relatively high. Although abdominal aorticaneurysms can be detected from routine examinations, the patient may notexperience any pain from the condition. Thus, if the patient is notreceiving routine examinations, it is possible that the aneurysm willprogress to the rupture stage.

Disadvantages associated with the conventional, prior art surgery, inaddition to the high mortality rate, are: the extended recovery periodassociated with the large surgical exposure in such open procedures;difficulties in suturing the graft, or tube, to the aorta; the loss ofthe existing thrombosis to support and reinforce the graft; theunsuitability of the surgery for many patients having abdominal aorticaneurysms; and the problems associated with performing the surgery on anemergency basis after the aneurysm has ruptured. As to the extent ofrecovery, a patient can expect to spend from 1 to 2 weeks in thehospital after the surgery, a major portion of which is spent in theintensive care unit, and a convalescence period at home from 2 to 3months, particularly if the patient has other illness such as heart,lung, liver, and/or kidney disease, in which case the hospital stay isalso lengthened. Since the graft must be secured, or sutured, to theremaining portion of the aorta, it is often difficult to perform thesuturing step because of thrombosis present on the remaining portion ofthe aorta, and that remaining portion of the aorta wall may be friable,or easily crumbled.

Since the thrombosis is totally removed in the prior art surgery, thenew graft does not have the benefit of the previously existingthrombosis therein, which could be utilized to support and reinforce thegraft, were the graft to be able to be inserted within the existingthrombosis. Since many patients having abdominal aortic aneurysms haveother chronic illnesses, such as heart, lung, liver, and/or kidneydisease, coupled with the fact that many of these patients are older,these patients are not ideal candidates for such surgery, which isconsidered major surgery. Such patients have difficulties in survivingthe operation. Lastly, once the aneurysm has ruptured, it is difficultto perform a conventional surgery on an expedited basis because of theextent of the surgery.

Accordingly, the prior art teaches various methods and apparatuses forrepairing an abdominal aortic aneurysm which is believed to lowermorbidity and mortality rate by not requiring an abdominal incision andgeneral anesthesia, not requiring suturing the graft to the remainingaortic wall, and which permits the existing aortic wall and thrombosistherein to be retained to reinforce and support the aortic graft. Anexample of such a method and apparatus is given in U.S. Pat. No.5,316,023 issued to Palmaz et al. on May 31, 1994; U.S. Pat. No.5,360,443 issued to Barone et al. on Nov. 1, 1994; U.S. Pat. No.5,578,071 issued to Parodi on Nov. 26, 1996; and U.S. Pat. No. 5,591,229issued to Parodi on Jan. 7, 1997, all of which are hereby incorporatedherein by reference.

Devices, such as the one shown in the above referenced Barone patent,use an improved method for repairing an abdominal aortic aneurysm in anaorta having two iliac arteries associated therewith. The deviceincludes first and second tubes, preferably made from a variety ofmaterials such as DACRON® and other polyester materials, TEFLON®(polytetrafluoroethylene), TEFLON® coated DACRON®, porous polyurethane,silicone, expanded polytetrafluoroethylene, and expanded polyurethane.It is preferred that all of the foregoing materials be porous to allowfor an intimal layer to form on the tubes. Each of the tubes areconnected to expandable and deformable tubular members, or stents. Thesestents can be similar in structure to those described in disclosed inU.S. Pat. No. 4,733,665 issued on Mar. 29, 1988; U.S. Pat. No.4,739,762, issued on Apr. 26, 1988; and U.S. Pat. No. 4,776,337 issuedon Oct. 11, 1988, all of the foregoing patents being in the name ofJulio C. Palmaz, each of which is incorporated herein by reference. Eachof the tube/stent structures are then disposed on the end of a ballooncatheter. Either both tubes are inserted into the same femoral artery orone of the tubes is inserted into one femoral artery of the patient andthe other tube is inserted into the other femoral artery of the patient.Thereafter the tubes are intraluminally delivered to the aorta, therebydisposing at least a portion of each tube within the abdominal aorticaneurysm. The balloons on the distal ends of the catheters are thenexpanded to expand and deform the tubular members, to force the tubularmembers radially outwardly into contact with the aorta and each other.This secures the tubular members and a least a portion of each tubewithin the aorta, whereby the tubes provide a bilateral fluid passagewaythrough the abdominal aortic aneurysm.

While the above mentioned devices would seem to work well, there is adesire to improve upon the device. More particularly, there was a needto ensure that most of the blood flowing through the abdomen flowsthrough the bilateral fluid passageways and not around them where itcould cause further damage. The precursor stent gasket described incommonly assigned European Patent Application EP 0947179, filed on Mar.29, 1999, European Patent Application EP 1000590 (A1), filed on Nov. 8,1999, and pending U.S. patent application Ser. No. 09/404,660 filed onSep. 24, 1999, the disclosures of which are hereby incorporated hereinby reference, limits the amount of blood which could leak around thebilateral fluid passageways and into the aneurysm. The precursor stentgasket is positioned within the infrarenal neck, between an abdominalaortic aneurysm and the renal arteries, of a patient to assist inrepairing the abdominal aortic aneurysm. The stent is designed to becoupled to the bilateral grafts for directing blood flow. The graft hasa distal end for positioning distal to the aneurysm, and a proximal endfor positioning proximal to the aneurysm. The precursor stent gasketincludes a substantially cylindrical expandable member having a proximalend, a distal end and an interior. The stent gasket further includes acompressible gasket member located within the interior of the expandablemember and attached thereto. The compressible member is substantiallyimpervious to blood when in a compressed state and is coupled the graft.This is so the coupled device can direct blood flow through the graft,with the gasket member substantially preventing blood from flowing intothe aneurysm.

While the above described devices are large improvements over the priorart, there has been a need for improvement. There has been a desire tohave a better device for attaching the graft material to the grafts usedin the above described devices. There has been a desire to have animproved stent gasket member for better attachment of the stent gasketmember to aortic wall. There has been a desire to have a mechanism forensuring that the stent gasket member is not prematurely deployed. Therehas been a desire to improve the design of the stent grafts to make themperform better. Lastly, there has been a desire to improve the grafts onthe stent grafts themselves to make them perform better duringdeployment. The following described invention provides such an improveddevice.

SUMMARY OF THE INVENTION

In accordance with the present invention there is provided a hollowsubstantially cylindrical radially expandable stent having proximal anddistal open ends and a longitudinal axis extending therebetween. Thestent is for deployment within a human body vessel, and is particularlyuseful in the manufacture of stent-grafts. The stent includes aplurality of hoops comprising a plurality of interconnected struts. Thestent has a proximal end hoop and a distal end hoop wherein the distalend hoop and the proximal end hoop have greater radial and longitudinalstrength than the hoops therebetween. The stent further includes aplurality of sinusoidal rings connecting adjacent hoops to one another.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other aspects of the present invention will best beappreciated with reference to the detailed description of the inventionin conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a precursor stent (shown without thegasket, in an expanded state) made in accordance with the presentinvention.

FIG. 2 is a view similar to that of FIG. 1 but including a gasket membermade in accordance with the present invention.

FIG. 3 is a cross-sectional view of the precursor stent of FIG. 2 takenalong section line 3—3 of FIG. 2.

FIG. 4 is a side elevational view of an endograft stent prior to theapplication of the graft material and shown in an expanded state.

FIG. 5 is a side elevational view of a longitudinally pleated graft tobe used in conjunction with the stent of FIG. 4 wherein the pleats arediscontinuous.

FIG. 6 is a partial side elevational view of another embodiment of thegraft wherein the longitudinal pleats are interrupted by circumferentialpleats.

FIG. 7 is an end elevational view of the graft as taken along view line7—7 of FIG. 5, the broken line work representing the graft in acompressed state.

FIG. 8 is a side elevational view of a complete stent-graft assemblyshown in a deployed state.

FIG. 9 is an enlarged partial plan view of an attachment tab at thecranial end of the stent as shown in the encircled area of FIG. 4.

FIG. 10 is a partial, exploded cross-sectional view of the attachmenttab as taken along section line 10—10 of FIG. 9 and includes a stapleand a portion of the graft material prior to affixing the graft to thestent.

FIG. 11 is a partial cross-sectional view of the attachment means aftercrimping the staple.

FIG. 12 is an enlarged partial plan view of an attachment node at thecaudal end of the stent as shown in the encircled area of FIG. 4.

FIG. 13 is a partial, exploded cross-sectional view of the attachmentnode as taken along section line 13—13 of FIG. 12 and includes a stapleand a portion of the graft material prior to affixing the graft to thestent.

FIG. 14 is a partial cross-sectional view of the attachment means aftercrimping the staple.

FIG. 15 is a partial, exploded perspective view of the caudal end of thestent-gasket, or endograft, and a portion of the delivery system shownafter its release from the delivery system.

FIGS. 16, 17 and 18 are sequential schematic perspective views showingthe method of positioning and deploying the stent-grafts, or endografts,after the precursor stent has already been deployed.

FIG. 19 is an elevational view of a fully deployed abdominal aorticrepair system made in accordance with the present invention.

FIG. 20 is a top plan view of the precursor stent as seen along viewline 20—20 of FIG. 19.

FIG. 21 is a photomicrograph of the gasket material prior to substantialcell ingrowth, as taken along section line 21—21 of FIG. 3.

FIG. 22 is a photomicrograph of the gasket material after substantialcell ingrowth, or biofusion, has taken place as taken along line 22—22of FIG. 19.

FIG. 23 is an elevational view of a delivery system for a stent gasketmade in accordance with the present invention, wherein the deliverysystem is inserted into an abdominal aortic aneurysm.

FIG. 24 is a view similar to that of FIG. 23 but showing the stentgasket partially deployed from its delivery system.

FIG. 25 is a view similar to that of FIG. 24 but showing the stentgasket fully deployed from its delivery system.

DETAILED DESCRIPTION OF THE INVENTION

One preferred use of the present invention is to treat abdominal aorticaneurysms. A better understanding of the present device and its use intreating abdominal aortic aneurysms will be achieved by reading thefollowing description in conjunction with the above incorporatedreferences. In addition, the terms cranial and distal, will refer to thedirection towards the head of the patient, and the terms caudal orproximal will refer to the direction away from the head of the patient.

Referring now to the drawings wherein like numerals indicate the sameelement throughout the views, there is shown in FIG. 1 a precursor stent10, shown in FIG. 1. As will be discussed below, precursor stent 10 isto be deployed within the infrarenal neck, between an abdominal aorticaneurysm and the renal arteries of a patient to assist in repairing theabdominal aortic aneurysm. The precursor stent 10 is designed to becoupled to one or more stent-grafts for directing blood flow through theaneurysm. The precursor stent 10 includes a substantially cylindricalself-expanding member 12 made from a plurality of interconnected struts.Self-expanding member 12 having two open ends, a proximal end 14, adistal end 16, and a longitudinal axis extending therebetween and aninterior 18. The precursor stent 10 further includes at least two, butpreferably 8 as shown in FIG. 1, spaced apart longitudinal legs 20 eachhaving proximal and distal ends 24 and 26 respectively. Preferably,there is a leg extending from each apex 11 of diamonds 13 (such diamondsbeing formed by the struts). The distal ends 26 of the legs are attachedto the proximal end 14 of the self-expanding member 12, the legsextending proximally away from the self-expanding member. At least one,but preferably each leg includes a flange 28 adjacent its proximal endwhich, as is described in greater detail below, allows for the stent tobe retrieved into its delivery apparatus after partial or fulldeployment of self-expanding member 12 so that it can be turned, orotherwise repositioned for proper alignment.

The self-expanding stents described herein are preferably made fromsuperelastic Nickel Titanium alloys (Nitinol). Descriptions of medicaldevices which use such alloys can be found in U.S. Pat. No. 4,665,906issued to Jervis on May 19, 1987, and European Patent Application EP0928606 filed on Jan. 8, 1999, both of which are hereby incorporatedherein by reference. Precursor stent 10 is preferably laser cut from atubular piece of Nickel Titanium Alloy and thereafter treated so as toexhibit superelastic properties at body temperature. Precursor stent 10is shown in the figures as being a diamond patterned stent, havingapproximately 8 diamonds, and when the stent is fully expanded thediamonds would have angles of 45–55 degrees at their distal and proximalends. However, precursor stent 10 can take on many different patterns orconfigurations.

In one embodiment of precursor stent 10, shown in most of the figuresbut removed from FIG. 1 for clarity, precursor stent 10 further includesa gasket member 30 (thereby forming a stent gasket or stent graft). Thisfeature can be better understood by referring to FIGS. 2 and 3. As seenfrom those figures, precursor stent 10 further includes a gasket member30. Gasket member 30 surrounds the self-expanding member 12 and can belocated along the interior of self-expanding member 12, the exterior ofself-expanding member 12 or both. The gasket member 30 helps impede anyblood trying to flow around the stent grafts, described below, afterthey have been inserted (as shown in FIG. 19) and from flowing aroundthe precursor stent 10 itself. For this embodiment gasket member 30 is acompressible member located along both the interior and the exterior ofself-expanding member 12.

Gasket member 30 can be made from any number of materials known to thoseskilled in the art. Preferably, gasket member 30 is made from an opencell polyurethane foam, however other flexible foams could be used, suchas polyethylene, polytetrafluoroethylene, other various polymermaterials which are woven or knitted to provide a flexible structuresuch as Dacron, polyurethane, polypropylene, polytetrafluoroethylene canalso be used. Preferably, the polyurethane foam has a cell size of50–100 pores per inch, and the density of the foam is 1.5–3.5 pounds percubic foot. Foams having these qualities absorb the blood like a sponge,contributing to blood stagnation which leads to thrombosis. In addition,it provides a trellis for cellular infiltration, and eventuallyscaffolds tissue incorporation. This helps to better anchor the devicewithin the body, thereby preventing stent migration. An example of sucha foam is shown in the photograph of FIG. 21. FIG. 21 shows a scanningelectron microscope of a open cell polyurethane foam havingapproximately 200–500 micrometer pores.

This ability of the tissue from the artery wall to incorporate theopen-pore foam structure has been termed by assignee as “Biofusion”.This tissue incorporation effect can best seen by referring to thephotographs of FIGS. 21 and 22. FIG. 22 shows histological photographsof connective tissue infiltrating and healing into the gasket member 30upon a 1 month follow-up of a device implanted into a target vessel.This ability of the tissue to heal into the foam creates a long termstable biological interface which, upon about six weeks afterimplantation, cannot be separated from the tissue without tearing thefoam material. The “Biofusion” effect has many advantages. It has thepotential to obviate late endo-leakage by preventing areas ofnon-organized clot from being displaced or recanalized. It is alsobelieved that “Biofusion” creates a connective tissue collar around thegasket that would prevent the aortic neck from dilating over time.Restriction of neck dilation avoids endoleakage paths and implantmigration that can be caused by an insufficient fit with the aorta. Theuse of such above described foams on stent grafts is not limited toabdominal aortic aneurysm repair, but could be applied in many stentgraft applications such as other aneurysm repair and vessel malformationand occlusion.

The foams described above are preferably highly compressible, so as tokeep the crimped profile low for better delivery. In addition, it ispreferable that the gasket member be substantially impervious to theflow of blood, at least when in a partially compressed state. When usedthroughout for the present invention, materials which are substantiallyimpervious to the flow of blood include materials which becomesubstantially impervious to the flow of blood after being saturated withblood. When the stent tubes and graft members, described below, areinserted and expanded within the gasket 30, the gasket 30 will compress.In this state, the gasket should be substantially impervious to blood soas to prevent blood from flowing through the interior 18 ofself-expanding member 12 and into the aneurysm. Gasket 30 can beattached to self-expanding member 12 by any number of means includingpolyurethane glue, a plurality of conventional sutures of polypropylene,DACRON®, or any other suitable material and attached thereto. Othermethods of attaching gasket 30 to self-expanding member 12 includeadhesives, ultrasonic welding, mechanical interference fit and staples.

As seen from FIG. 2, precursor stent 10 preferably includes a number ofradiopaque markers 15. As shown, markers 15 are coils of radiopaquemetal, wrapped around the struts of the precursor stent. The markers arepositioned along the stent so that the physician can better know theexact position of the stent during deployment when viewed underfluoroscopy. Markers 15 are preferably made from 0.010″ diametertantalum (Ta) wire wrapped tightly around the struts. Three markers areused; two near the distal end of the device, and one proximal thereto.The distal two are 180° apart, and the proximal one is equally spacedbetween the distal two when viewed from a rotation where the top two arespaced as far apart as possible. This proximal marker then aids properrotational positioning of the device. Specifically, one of the distalmarkers is 5 mm long and is adjacent to the aperture 34 in the gasket;the other is 2 mm long and is adjacent to the hole 36. Since hole 36should be placed adjacent to the right side of the aneurysm, as shown inFIG. 19, the small distal marker should be placed on the right side; theproximal marker (also 2 mm long) should appear fluoroscopically to bemidway between the upper two markers.

As seen from FIGS. 2 and 3, the precursor stent further includes anocclusive member 32 attached to self-expanding member 12. The occlusivemember covers at least a portion of the interior of the self-expandingmember. The occlusive member covers the interior of self-expandingmember 12 in such a way that a lumen 5 of the expandable member whichprovides passageway from its proximal end 14 to its distal 16 is atleast partially blocked. Occlusive member 32 further includes twoopenings 34 and 36 extending therethrough. Opening 34 is relativelysmall and is designed to receive a guidewire, wherein such guidewirehelps deliver precursor stent 10 to the target site. Opening 36 isrelatively large, and is designed to receive another guidewire having aloaded stent graft proximal thereto. As will be explained below, theocclusive member helps to ensure proper side by side placement of thetwo stent-grafts.

Precursor stent 10 acts to temporarily scaffold the gasket member withinthe body, until the stent-grafts are deployed (see FIG. 19). Shown inFIG. 4 is a preferred embodiment of a stent 40 for use in a stent-graftin accordance with the present invention. Stent 40 is made from aplurality of interconnected struts 44, and has an interior surface 43Aand an exterior surface 43B (shown in FIG. 15). FIG. 4 shows stent 40 inits fully deployed, un-crimped state. As will be appreciated by thoseskilled in the art, stent 40 should be crimped to a smaller diameterprior to insertion into a patient. Stent 40 is preferably made fromsuperelastic Nitinol, and have enough outward force to stay within thebody, without the use of the precursor stent 10. Stent 40 is preferablymade from a single tube of Nitinol, having the following features lasercut therein. Stent 40 has a number of hoops 42 comprising a number ofstruts 44 making a diamond shape configuration, wherein each hooppreferably has 9 diamonds. Stent 40 further includes a number ofsinusoidal rings 50 for connecting adjacent hoops to one another. Thesinusoidal rings are made from a number of alternating struts 52,wherein each ring preferably has 54 struts. As will be explained indetail below in connection with the discussion of FIGS. 9–14, stent 40includes a distal attachment means 54 and a proximal attachment means56.

Stent 40 has a proximal hoop 48 and a distal hoop 46, also referred toas anchors. The proximal hoop is flared, and is exposed after the grafthas been attached thereto. The diamond pattern for the anchors, as wellas the other hoops, provide the hoops with radial and longitudinalstiffness. The longitudinal strength provides for better mechanicalfixation of stent 40 to a graft (described below). The radial strengthprovides the distal hoop 46 with better attachment and sealing to stentgasket or precursor stent 10, and provides the proximal hoop 48 withbetter fixation and sealing to the arterial wall. In one preferredembodiment, the proximal and distal hoops have greater radial andlongitudinal strength than the hoops therebetween. This creates astent-graft having stiff ends for anchoring, but a more flexible bodyfor navigation through the vasculature. The stiffer ends can beaccomplished by changing the dimensions of the struts for the end hoops,or by varying the heat treatment of the end hoops during manufacture.The rings allow the stent to bend more easily, and generally provide formore flexibility when the stent is being delivered through a tortuousvessel. When a non-compliant graft is attached to stent 40, the strengthof the diamond hoops scaffolds any graft folding into the blood flowlumen, while maintaining a tight kink radius.

As stated above, stent 40 preferably has a graft member attachedthereto. The graft member covers at least a portion of the interior orexterior of stent 40, and most preferably covers substantially all ofthe exterior of the stent 40. Shown in FIGS. 5–7 is an embodiment of atubular graft 60 for use with the present invention. Graft member 60 canbe made from any number of materials known to those skilled in the art,including woven polyester, Dacron, Teflon or polyurethane. Graft 60 hasa proximal end 64, a distal end 62, and a longitudinal axis 66 extendingtherebetween. As seen from FIG. 5, graft 60 has a plurality oflongitudinal pleats 68 extending along its surface, and being generallyparallel to longitudinal axis 66. As seen from FIG. 7, when the graft 60is collapsed around its center, much as it would be when it is deliveredinto a patient, the pleats in the graft come together as a series ofradially oriented regular folds which pack together efficiently, so asto minimize wrinkling and other geometric irregularities. Uponsubsequent expansion, graft 60 assumes its natural cylindrical shape,and the pleats or folds uniformly and symmetrically open.

The pleats provide for a more uniform crimping of the graft 60, whichhelps the assembled stent graft (stent 40 attached to graft 60, as willbe discussed below) to crimp into a relatively low profile deliverysystem, and provides for a controlled and consistent deploymenttherefrom. In addition, pleats 68 help facilitate stent graftmanufacture, in that they indicate the direction parallel to thelongitudinal axis, allowing stent to graft attachment along these lines,and thereby inhibiting accidental twisting of the graft relative to thestent after attachment. The force required to push the stent-graft outof the delivery system may also be reduced, in that only the pleatededges of the graft make frictional contact with the inner surface of thedelivery system. One further advantage of the pleats is that blood tendsto coagulate generally uniformly in the troughs of the pleats,discouraging asymmetric or large clot formation on the graft surface,thereby reducing embolus risk.

In one preferred embodiment, the depths of pleats 68 range from 0.06inch to 0.07 inch for a graft having a crimped inner diameter of 0.08inch and a crimped outer diameter ranging from 0.131 inch to 0.155 inch.This combination of pleat depth and inner and outer diameters results inpleat frequencies that generally preclude the existence of excessiveradial graft flaps across the range of diameters for the device.

As seen best from FIG. 6, graft 60 preferably includes a plurality ofradially oriented pleat interruptions 70. The pleat interruptions aresubstantially circular and are oriented perpendicular to longitudinalaxis 66. While the pleats 68 mentioned above provide for a uniformcrimping of graft 60, they may tend to increase kink propensity sincethey run perpendicular to the graft's natural folding tendencies whenbent along its axis. Pleat interruptions 70 allow the graft to betterbend at selective points. This design provides for a graft that has goodcrimpability and improved kink resistance.

FIG. 9 shows an up-close view of distal attachment means 54 of stent 40.Distal hoop 46 of stent 40 has a plurality of attachment tabs 82extending therefrom which are formed from the joining together of twostruts 44(a) and 44(b). Attachment means 54 comprises two apertures 84(first aperture) and 86 (second aperture) extending therethrough. Asseen from FIG. 10, graft 60 also preferably includes two apertures 74and 76 (which can be initially created during the attachment process)which are coextensive with apertures 84 and 86 when graft 60 is placedover stent 40 for attachment. Finally, attachment means 54 includes astaple 90 having a crown 92 and attachment legs 94 (first leg) and 96(second leg) extending therefrom. Attachment leg 96 extends throughapertures 76 and then aperture 86. Simultaneously, leg 94 bends aroundnotch 85, but it does not penetrate graft 60 like leg 96. Thereafter,attachment leg 94 and 96 are bent back through apertures 84 and 74 andin towards crown 92, so as to attach the distal end of the graft to thedistal end of the stent as shown in FIG. 11. Legs 94 and 96 make contactwith crown 92 after attachment. Preferably, there are six staples at thedistal end.

FIG. 12 shows an up-close view of proximal attachment means 56 of stent40. Proximal hoop 48 of stent 40 has a plurality of members 110occurring at the joining of four struts 44(c)–44(f). Attachment means 56comprises three apertures 112 (first aperture), 114 (middle aperture)and 116 (second aperture) extending therethrough. As seen from FIG. 13,graft 60 also preferably includes three apertures 121, 123 and 125(which can be initially made during the attachment process by puncturingtherethrough with a staple) which are coextensive with apertures 112,114 and 116 when graft 60 is placed over stent 40 for attachment.Finally, attachment means 56 includes a staple 120 having a crown 122and legs 124 (first leg) and 126 (second leg) extending therefrom. Legs124 and 126 extend through apertures 112 and 116 and then throughapertures 121 and 125 respectively. Thereafter, legs 124 and 126 arebent back through apertures 124 and 114 and in towards crown 122, so asto attach the proximal end of the graft to the proximal end of the stentas shown in FIG. 14. Legs 124 and 126 make contact with crown 122 afterattachment. Preferably, there are three staples at the proximal end.

The above staple aperture design has many advantages for attaching astent to a graft. Because the legs of the staple are folded around andimbedded within a pocket or the like, any risk of puncturing aninflation balloon is minimized. In addition, the structural integrity ofthe stent-graft is believed to be increased in that these staples shouldmore securely attach the graft to the stent compared to prior artdesigns which use suture or adhesives to attach the graft to the stent.Staples 90 and 120, illustrated in FIG. 8, can be made from any numberof materials known in the art, including tantalum alloys, platinumalloys or stainless steel, such as 316 LVM stainless steel. The staplesmay take on other configurations and shapes, and can be coated forlubricity purposes. Having the staples made from a radiopaque materialhelps the physician in accurately deploying the device.

Another feature of stent-graft 80, illustrated in FIG. 8, can be betterunderstood by referring to its delivery apparatus 130 shown in FIG. 15.Apparatus 130 is very similar to other self-expanding delivery apparatusdescribed in the above incorporated references. Apparatus 130 includesan outer sheath 132 which is essentially an elongated tubular member,similar to ordinary guiding catheters which are well known to those ofordinary skill in the art. An example of a particularly preferred outersheath is described in commonly assigned U.S. Pat. No. 6,019,778 issuedon Feb. 1, 2000, which is hereby incorporated herein by reference.Sheath 132 has a distal end 134 and a proximal end (not shown).Apparatus 130 also includes an inner shaft 140 located coaxially withinthe outer sheath 132 prior to deployment. The inner shaft has a distalend 142 and a proximal end (not shown). The distal end 142 of the shafthas at least two grooves 144 disposed thereon. Stent 40 preferably has anumber of flanges 41 disposed at its proximal end. The flanges on thestent are set within the grooves of the inner shaft, thereby releasablyattaching the stent to the inner shaft. The delivery system forprecursor stent 10 is also similar, having an outer sheath and an innershaft wherein the shaft has grooves to receive flanges 28 of precursorstent 10.

The advantages of flanges 41 on stent 40 and flanges 28 on precursorstent 10 and the grooves on the inner shafts of their delivery system isthat they may allow for partial deployment of the stents and recapturewithin the delivery apparatus if the physician is not pleased with theposition of the stent. The present invention allows the physician topartially deploy one of the stents (precursor stent 10 or stent-graft80) while the flanges remain within the sheath. The flange groovecombination allows the physician to “pull” the stent back into thedelivery device if the placement is not optimal.

The advantages of flanges 28 on precursor stent 10 and the grooves onthe inner shafts of their delivery system can best be described byreferring to FIGS. 23–25. FIG. 23 shows an exemplary embodiment of thedelivery apparatus 130 for stent gasket or precursor stent 10. Apparatus130 is very similar to other self-expanding delivery apparatus describedin the above incorporated references. Apparatus 130 includes an outersheath 132 which is essentially an elongated tubular member, similar toordinary guiding catheters which are well known to those of ordinaryskill in the art. An example of a particularly preferred outer sheath isdescribed in commonly assigned U.S. Pat. No. 6,019,778 issued on Feb. 1,2000, which is hereby incorporated herein by reference. Apparatus 130also includes an inner shaft 140 located coaxially within the outersheath 132 prior to deployment. Inner shaft 140 includes a number ofgrooves 144. As seen from FIG. 24, this arrangement allows for partialdeployment of precursor stent 10 and recapture within the deliveryapparatus if the physician is not pleased with the initial position ofthe stent. The present invention allows the physician to partiallydeploy precursor stent 10 while the flanges remain within the sheath.The flange groove combination allows the physician to “pull” the stentback into the delivery device if the placement is not optimal.

In order to prevent the physician from prematurely completely deployingthe precursor stent 10, a releasable stop 150 is preferably placed onthe inner shaft. The stop could be a ring having a greater diameter thanthe sheath, so that as the sheath is pulled proximally along the innershaft it hits the stop, and prevents full deployment of the entireprecursor stent 10. The stop is preferably releasably attached to theinner member so that it can be released from its engagement with theinner shaft to allow the outer member to slide back enough to fullydeploy the entire precursor stent 10 within the body.

FIGS. 16–18 generally show how the above described invention is deployedwithin the body. Prior to what is shown in FIG. 16, the physician wouldfirst insert the precursor stent 10, having the gasket member attachedthereto, into the body with the aid of guidewire 200, which remains inthe body after deployment. The stent gasket or precursor stent 10 isdelivered through one of the patient's femoral arteries and into a firstiliac artery 1 and deployed within the infrarenal neck 3. Thereafter,the delivery device for the precursor stent 10 is removed, withoutremoving guidewire 200, and another guidewire 202 is inserted throughthe other femoral artery and into the other iliac artery 2. Because thesize of opening 36 in occlusive member 32 is relatively large, thephysician can only maneuver guidewire 202 therethrough. Thereafterstent-graft delivery apparatus 130 a and 130(b) are inserted intofemoral arteries and into the iliac arteries 1 and 2 by sliding themover guidewires 200 and 202, and accurately delivering them to thetarget site. Thereafter, both stent-grafts 80(a) and 80(b) are eitherseparately or simultaneously deployed within the body. Ultimately thedistal ends of the stent grafts reside level with each other, just belowthe renal arteries, and some distance above the distal end of the stentgasket. The bodies of the stent grafts pass through the stent gasket andthrough the aneurysm sac.

After properly delivery, precursor stent 10 and stent-grafts 80(a) and80(b) should appear as they do in FIG. 19. Precursor stent 10 along withits attached gasket member 30 are firmly secured within the infrarenalneck 3. The outward force of the stent-grafts 80 on the precursor stent10 help to secure the device within the body. The proximal ends of thestent-grafts are firmly attached to the iliac arteries 1 and 2.Thereafter blood will flow from the abdominal aorta 302 down into andthrough stent-grafts 80(a) and 80(b) and into iliac arteries 1 and 2,thereby bypassing the aneurysmal sack 304. If all the components areplaced accurately, distal end of the device should appear as it does inFIG. 20.

In order to prevent the physician from prematurely completely deployingthe precursor stent 10, a releasable stop is preferably placed on theinner shaft. The stop could be a ring having a greater diameter than theouter member, so that as the outer member is pulled proximally along theinner shaft it hits the stop, and prevents full deployment of the entireprecursor stent 10. The stop is preferably releasably attached to theinner member, by threads, snap fit or the like, so that it can bereleased from its engagement with the inner shaft to allow the outermember to slide back enough to fully deploy the entire precursor stent10 within the body.

Although particular embodiments of the present invention have been shownand described, modification may be made to the device and/or methodwithout departing from the spirit and scope of the present invention.The terms used in describing the invention are used in their descriptivesense and not as terms of limitations.

1. A monolithic, hollow substantially cylindrical radially expandablestent having proximal and distal open ends and a longitudinal axisextending therebetween, said stent for deployment within a human bodyvessel, said stent comprising: a. a plurality of hoops comprising aplurality of interconnected struts forming a substantially diamond shapeconfiguration, said stent having a proximal end hoop and a distal endhoop, wherein said distal end hoop and said proximal end hoop areconfigured to have greater radial and longitudinal strength than thehoops therebetween and said proximal hoop is flared; b. a plurality ofsinusoidal rings connecting adjacent hoops to one another, saidsinusoidal rings being formed from a plurality of alternating struts,the plurality of alternating struts being substantially shorter inlength than the plurality of interconnected struts of the plurality ofhoops, each of the plurality of sinusoidal rings having more than twicethe number of struts forming the plurality of hoops and each of saidplurality of sinusoidal rings having a periodic structure of less thanone-half of the periodic structure of said plurality of hoops, whereinthe union of each of the plurality of sinusoidal rings and each of theplurality of hoops is made at the apex of at least one diamondconfiguration of the plurality of hoops and the apex of at least oneintersection of the plurality of alternating struts of the sinusoidalrings; and c. proximal and distal attachment devices for securing agraft member to the substantially cylindrical radially expandable stent,the proximal attachment device being positioned distal of the proximalopen end of the stent such that the proximal end hoop of the stent isconfigured to be exposed to a body vessel, said proximal and distalattachment devices comprising tabs formed from the joining of two strutsand having at least two apertures therein, wherein the plurality ofhoops, the plurality of sinusoidal rings and the proximal and distalattachment devices form a monolithic structure.
 2. The stent accordingto claim 1 wherein said stent is a self-expanding stent.
 3. The stentaccording to claim 2 wherein said stent is made from a superelasticnickel titanium alloy.
 4. The stent according to claim 1, wherein atleast one of said distal and proximal end hoops is formed so as to havea larger diameter than a hoop adjacent thereto.